The aim of these research efforts is to explore the psychobiology of cognition in man. We attempt to interrelate psychological and biological determinants of the various components of cognition. Studies have been designed to understand the specific and discrete psychobiological mechanisms that define the acquisition, processing, encoding, consolidation, and retrieval of experience. Other studies have also begun to examine the meta-cognitive processes involved in learning and memory. Experiments are also designed to examine the biological and psychological determinants of psychiatric and neuropsychiatric alterations in cognitive processes in adults and children. Specific forms of central nervous system dysfunctions (e.g., as defined by type of lesion in neuropsychiatric disorders) may affect specific and distinct components of cognitive processing. Similarly, psychoactive drugs that affect discrete aggregates of neurons may alter different aspects of cognition and information processing. Based on empirical studies of clinical populations (e.g., depression, Alzheimer's disease, Korsakoff's disease, forms of learning impairments in children) and several types of psychoactive agents (cholinergic drugs, noradrenergic drugs, neuropeptides), it has been possible to begin to define the psychobiological relationships between semantic and episodic memory, encoding processes, and effortful (active) cognitive operations as opposed to automatic cognitive processes.